Add taco seasoning to the sausageand combine well to incorporate. Then cook sausage on one side of a large non-stick pan or well-seasoned cast iron skillet over medium high heat until browned and cooked through about 10 minutes. At the same time, add oil and hashbrowns to the other side of the pan and cook until nicely browned on the bottom, then flip over and brown on the other side. It should take about 5 minutes per side. Remove sausage and hashbrowns from pan and transfer to a large plate.
Meanwhile, in a medium bowl, whiskeggs with sour cream, salt, and pepper.
Add the egg mixture and butter to the pan and cook slowly, scraping them up with a high-temp silicone spatula until most of the liquid has thickened and the eggs are soft, about 3 minutes.
At the same time you are cooking the eggs, place tortillas in a toaster until warmed through. If you have a gas stove, you could also grill over the gas flame on the stove top using tongs.
Fold the warm fluffy eggs into warmed tortillas, top with sausage, crumbled hashbrowns, diced tomato, a sprinkle of cheese and any additional toppings you want like salsa. Eat immediately!